JP2000344992A - Resin composition for laser marking and molded article formed from the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition for laser marking capable of exhibiting a clear white marking without damaging impact resistance by compounding a specific rubber-containing graft copolymer, a specific maleimide-based copolymer, a coloring agent and the like. SOLUTION: This composition is obtained by including (D) 0.001-5 pts.wt. of a coloring agent to a resin composition composed of (A) 10-50 pts.wt. of a rubber-containing graft copolymer prepared by grafting at least one or more kinds selected from (ii) a vinyl cyanide monomer, (iii) an aromatic vinyl monomer and (iv) another vinyl monomer copolymerizable with one of these monomers in the presence of (i) a rubbery polymer, (B) 0-50 pts.wt. of a maleimide-based copolymer prepared from 5-45 wt.% of the component ii, 40-90 wt.% of the component iii and (v) 5-55 wt.% of a maleimide monomer, (C) 5-90 pts.wt. of a vinyl cyanide-based copolymer prepared from 3-45 wt.% of the component ii, 90-20 wt.% of the component iii and 0-80 wt.% of the component iv [herein, the components (A+B+C)=100 pts.wt.].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition and a molded article comprising the same, which can give a clear white marking when irradiated with a laser beam.

[0002]

2. Description of the Related Art Acrylonitrile-butadiene-styrene copolymer (ABS resin) has an excellent balance between moldability and impact resistance, and is widely used in applications for OA equipment and home electric appliances. Such molded articles are often displayed by characters and the like, and conventionally, printing using ink or the like such as silk printing or tampo printing or display by a seal has been performed.

However, in recent years, attention has been paid to a method of marking with a laser beam which can be performed easily and efficiently. This is a technique that enables marking when the resin foams or decomposes or the resin surface is carbonized upon irradiation with a laser beam.

[0004] As these technical methods, a method of blending carbon black or graphite with a material (Japanese Patent Application Laid-Open No. 57-116620), a copolymer comprising a (meth) acrylate monomer and a vinyl monomer is disclosed. Method for blending a polymer with a rubber-containing styrenic resin
JP-A-112968) and a method of blending another thermoplastic resin with a rubber-containing styrenic resin (Japanese Patent Laid-Open No. 9-1).
No. 00390) has been proposed.

However, when the resin composition contains an aromatic vinyl monomer, a vinyl cyanide monomer and other monomers in a certain amount or more, the sharpness of a marking portion is reduced. When a copolymer comprising a (meth) acrylate monomer and a vinyl monomer is used, the impact resistance is reduced, and furthermore, even if other thermoplastic resins are added, the sharpness is not sufficient. There was a problem.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a resin composition capable of providing a clear white marking by irradiating a laser beam without impairing impact resistance, and a molded article comprising the same. The purpose is to provide.

The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, it has been found that the amount of unreacted aromatic vinyl monomers and vinyl cyanide monomers in the resin composition is reduced, and that By adding triiron tetroxide and / or fine carbon to part of the agent, without impairing the impact resistance,
Further, they have found that clear white markings can be exhibited even in the heat-resistant resin composition and the flame-retardant resin composition, and have finally completed the present invention.

[0008]

That is, the present invention relates to a vinyl cyanide-based monomer (b), an aromatic vinyl-based monomer (c) and a copolymer thereof in the presence of a rubbery polymer (a). 10 to 50 parts by weight of a rubber-containing graft copolymer (I) obtained by grafting at least one monomer selected from other polymerizable vinyl monomers (d), vinyl cyanide monomer (B) 5 to 45% by weight, aromatic vinyl monomer (c) 40 to 90% by weight and maleimide monomer (e)
Maleimide copolymer (II) consisting of 5 to 55% by weight
0 to 50 parts by weight, and vinyl cyanide monomer (b)
3 to 45% by weight, aromatic vinyl monomer (c) 90 to 2
(I) + (II) comprising 5 to 90 parts by weight of 0% by weight and 0 to 80% of another vinyl copolymer (d) copolymerizable therewith. +
(III) = Coloring agent (IV) based on 100 parts by weight
0.001 to 5 parts by weight, and the unreacted aromatic vinyl monomer (c), vinyl cyanide monomer (b) and other monomers (d) in the resulting composition. ) Is 4
000 ppm or less.

[0009]

Embodiments of the present invention will be described below.

The rubbery polymer (a) used for the rubber-containing graft copolymer (I) in the present invention is a diene rubber, an acrylic rubber, an ethylene rubber or the like, and specific examples are polybutadiene, polybutadiene, and polybutadiene. (Butadiene-styrene), poly (butadiene-acrylonitrile), polyisoprene, poly (butadiene-butyl acrylate), poly (butadiene-methyl acrylate), poly (butadiene-methyl methacrylate), poly (butyl acrylate-methacrylic) Acid), poly (butadiene-
Ethyl acrylate), ethylene-propylene rubber, ethylene-propylene-diene rubber, poly (ethylene-
Isobutylene), poly (ethylene-methyl acrylate)
And the like. These rubbery polymers are used in one kind or in a mixture of two or more kinds. Among these rubbery polymers, polybutadiene, poly (butadiene-styrene), poly (butadiene-acrylonitrile) and ethylene-propylene rubber are particularly preferably used in view of impact resistance.

Specific examples of the vinyl cyanide monomer (b) used in the rubber-containing graft copolymer (I), maleimide copolymer (II) and vinyl cyanide copolymer (III) in the present invention Examples thereof include acrylonitrile and methacrylonitrile, and one or more kinds can be used. Among them, acrylonitrile is particularly preferable in terms of chemical resistance.

Specific examples of the aromatic vinyl monomer (c) used in the rubber-containing graft copolymer (I), maleimide copolymer (II) and vinyl cyanide copolymer (III) in the present invention Are styrene, α-methylstyrene, orthomethylstyrene, paramethylstyrene,
Examples thereof include para-t-butylstyrene and halogenated styrene, and one or more kinds can be used. Of these, styrene and α-methylstyrene are particularly preferred in view of moldability, and styrene is more preferred.

Specific examples of other copolymerizable vinyl monomers (d) used in the rubber-containing graft copolymer (I) and the vinyl cyanide copolymer (III) in the present invention include acrylic acid Unsaturated carboxylic acids such as methacrylic acid, (meth) acrylic esters such as methyl acrylate, methyl methacrylate and butyl acrylate, (meth) acrylamides such as acrylamide, methacrylamide and N-methylacrylamide, maleimide, N-
Maleimides such as methylmaleimide, and unsaturated carboxylic anhydrides such as maleic anhydride, citraconic anhydride and aconitic anhydride can be cited. Among them, methyl methacrylate and N-phenylmaleimide are preferred in terms of moldability. Is preferred.

In the present invention, the maleimide copolymer (I)
Specific examples of the maleimide-based monomer (e) used for I) include N-phenylmaleimide, N-cyclohexylmaleimide, N-methylmaleimide, and maleimide. Among them, N-phenylmaleimide is preferred in terms of moldability. Particularly preferably used.

The content of the rubbery polymer (a) in the rubber-containing graft copolymer (I) in the present invention is preferably from 10 to 80% by weight, more preferably from 40 to 70% by weight, from the viewpoint of impact resistance. . Further, the content of the vinyl cyanide monomer (b) in the rubber-containing graft copolymer (I) is preferably from 3 to 70% by weight from the viewpoint of color tone stability, and more preferably from 10 to 40% by weight. . Further, the content of the aromatic vinyl monomer (c) in the rubber-containing graft copolymer (I) is preferably from 10 to 80% by weight in view of color stability, more preferably from 20 to 50% by weight. . The graft ratio is preferably from 10 to 80% by weight, and the reduced viscosity of the copolymer of the graft component is preferably from 0.2 to 0.8 dl / g from the viewpoint of impact resistance.

In the present invention, the maleimide copolymer (I)
The structural unit of the monomer component of I) is 5 to 45% by weight of a vinyl cyanide monomer (b) and an aromatic vinyl monomer (c).
40 to 90% by weight and the maleimide monomer (e)
55% by weight.

Among them, vinyl cyanide monomer (b)
5 to 40% by weight, aromatic vinyl monomer (c) 30 to 5
Those in the range of 5% by weight and 30 to 55% by weight of the maleimide monomer (e) are preferred in terms of the balance between impact resistance and heat resistance.

If the amount of the vinyl cyanide monomer is less than 5% by weight, the chemical resistance is poor, and if it exceeds 45% by weight, the color tone stability is reduced. When the content of the aromatic vinyl monomer (c) is less than 40%, the color stability of the thermoplastic resin composition for sheet molding at the time of melting is significantly reduced, and when it exceeds 90% by weight, the chemical resistance is lowered. Inferior. Maleimide monomer (e)
Is less than 5% by weight, heat resistance is not sufficient, and if it exceeds 55% by weight, impact resistance is poor.

The glass transition temperature of the maleimide copolymer (II) in the present invention is 12 from the viewpoint of heat resistance.
0 ° C. or higher is preferable, and 210 ° C. or lower is preferable from the viewpoint of impact resistance. More preferably, it is 135 to 200 ° C.

In the present invention, the constituent units of the monomer component of the vinyl cyanide copolymer (III) are 3 to 45% by weight of the vinyl cyanide monomer (b), Body (c) is 90 to 20% by weight. Preferably, the content is 20 to 40% by weight of the vinyl cyanide monomer (b) and 80 to 60% by weight of the aromatic vinyl monomer (c).

3% by weight of vinyl cyanide monomer (b)
Less than 90% by weight of the aromatic vinyl monomer (c)
If it exceeds, the chemical resistance is not sufficient. If the content of the vinyl cyanide-based monomer (b) exceeds 45% by weight and the content of the aromatic vinyl-based monomer (c) is less than 20% by weight, the color tone stability decreases.

Although the molecular weight of the vinyl copolymer (III) is not particularly limited, the reduced copolymer has a reduced viscosity of 0.30 to 0.30.
Those having a range of 0.90 dl / g, particularly 0.35 to 0.85 dl / g are preferably used in view of impact resistance and fluidity.

In the resin composition of the present invention, the rubber-containing graft copolymer (I) and the maleimide-based copolymer (II)
And the vinyl cyanide-based copolymer (III) are mixed in an amount of 10 to 50 parts by weight of the rubber-containing graft copolymer (I), 0 to 50 parts by weight of the maleimide-based copolymer (II), It is necessary that the amount of the polymer (III) is 5 to 90 parts by weight ((I) + (II) + (III) =
100 parts by weight). Rubber-containing graft copolymer (I) is 1
If it is less than 0 parts by weight, the impact strength is not sufficient, and if it exceeds 50 parts by weight, the laser marking property is poor. When the amount of the maleimide-based copolymer (II) exceeds 50 parts by weight, the impact resistance is poor. If the amount of the vinyl cyanide copolymer (III) is less than 5 parts by weight, the chemical resistance is not sufficient, and if it exceeds 90 parts by weight, the color tone stability is poor.

As the coloring agent (IV) in the present invention,
Examples thereof include organic pigments, inorganic pigments, and dyes. Of these, triiron tetroxide and / or fine carbon black having a particle diameter of 50 nm or less are preferable. By using these coloring agents, the white character coloring property (whiteness) and the sharpness are both further improved, and the laser marking property is further improved.

The coloring agent (IV) is a resin composition A ((I)
+ (II) + (III) = 100 parts by weight)
. It is necessary to be 001 to 5 parts by weight, preferably 0.001 to 4 parts by weight. (IV) If the coloring agent is less than 0.001 part by weight, the laser marking property is insufficient, and if it exceeds 5 parts by weight, the impact resistance is poor.
In the case of triiron tetroxide as the coloring agent (IV), 0.1
To 2 parts by weight, preferably 0.1 to 1.5 parts by weight, if the fine carbon black has a particle diameter of 50 nm or less, the fine carbon black is 0.1 to 0.2 parts by weight.
001 to 0.1 parts by weight, preferably 0.003 to 0.0
When the content is 8 parts by weight, the laser marking property is excellent. It is also possible to use triiron tetroxide and fine carbon black in combination. When the amount of triiron tetroxide is less than 0.1 part by weight and the amount of fine carbon black is less than 0.001 part by weight, the laser marking property is insufficient. If the amount is more than the weight part, whiteness and sharpness are remarkably reduced due to foaming and carbonization. The particle diameter of the fine carbon black is preferably 50 nm or less, and more preferably 10 to 30 nm, so that the laser marking property is excellent. Particle size of carbon black is 50nm
If it exceeds, the whiteness decreases.

In the resin composition of the present invention, the total of the unreacted aromatic vinyl monomer (c), vinyl cyanide monomer (b) and other monomer (d) in the composition Is 40
The sharpness of the marking is excellent by suppressing the content to 00 ppm or less, preferably 3000 ppm or less, and more preferably 2000 ppm or less. If it exceeds 4000 ppm, the sharpness of the marking will be poor. Similarly, when the total amount of the unreacted monomers is suppressed to 4000 ppm or less for the black color,
The sharpness of the marking is improved.

In the resin composition of the present invention, polybromodiphenyl ether, tetrabromobisphenol-
A, halogenated compounds such as brominated epoxy oligomers, brominated polycarbonate oligomers, phosphorus compounds,
5 to 5 flame retardants and flame retardant assistants (V) such as antimony trioxide
0 parts by weight, UL94, V-2, V-1, V-0
Similarly, in a molded article provided with a level of flame retardancy, a composition excellent in laser marking properties can be obtained by appropriately adjusting the amount of the colorant and unreacted monomer in the resin composition.

In the present invention, 2,6-di-t-butyl-4-methylphenol, 4,
Phenolic antioxidants such as 4'-butylidene-bis (3-methyl-6-t-butylphenol); phosphorus-based oxidations such as tris (mixed, mono- and dinonylphenyl) phosphites and diphenyl isodecyl phosphite Antioxidants, sulfur-based antioxidants such as dilauryl thiodipropionate, dimyristyl thiodipropionate diasterial thiodipropionate, 2-hydroxy-4
-Octoxybenzophenone, 2- (2-hydroxy-
UV absorbers such as 5-methylphenyl) benzotriazole, bis (2,2,6,6, -tetramethyl-4-
Light stabilizers such as piperidinyl), antistatic agents such as hydroxylalkylamine and sulfonate, lubricants such as ethylenebisstearylamide and metal soap, glass fibers,
It is also possible to add an inorganic filler such as carbon fiber.

Hereinafter, an example of a method for producing the resin composition for laser marking of the present invention will be described. The method for producing the rubber-containing graft copolymer (I), the maleimide-based copolymer (II), and the vinyl-based copolymer (III) in the present invention is not particularly limited. Emulsion polymerization, suspension polymerization, bulk polymerization It can be produced by a polymerization method, a solution polymerization method, or a polymerization method based on a combination thereof. As a means for modifying with a rubbery polymer, a method in which a monomer that forms a resin phase in the presence of rubbery material is graft-polymerized by an emulsion polymerization method, an emulsion-suspension polymerization method, a bulk polymerization method, or the like is employed. . At this time, the graft ratio is 15 to 100 from the viewpoint of mechanical properties.
%, More preferably 20 to 70%
It is.

With respect to the method for producing the resin composition for laser marking of the present invention, various methods such as melt kneading with a Banbury mixer, a roll and a single-screw or multi-screw extruder can be employed.

The resin composition for laser marking of the present invention can be molded by a known method currently used for molding thermoplastic resins such as injection molding, extrusion molding, blow molding, vacuum molding, compression molding, and gas assist molding. And is not particularly limited.

The uses of these molded articles are as follows: electricity,
Although there are no particular restrictions on electronics, automobiles, machines, miscellaneous goods, etc., the characteristics of the molded article of the present invention are effective for applications in which characters and symbols are printed and displayed. Above all, it prints and displays the housing parts of OA equipment, electrical and electronic products, structural parts of refrigerators, miscellaneous goods such as pachinko trays, sanitary uses such as toilets and kitchens, and interior and exterior materials for automobiles. Can be applied to the site.

Methods for measuring physical properties : Methods for measuring the properties of the resin composition for laser marking of the present invention are described below. For general properties such as laser marking property and impact resistance, test pieces were molded by injection molding and measured according to the following test methods. (1) Graft ratio Acetone was added to a predetermined amount (m) of the graft copolymer, and the mixture was refluxed for 3 hours. p. m. (1000
After centrifugation at 0 G) for 40 minutes, the insoluble matter was filtered, and the insoluble matter was dried under reduced pressure at 60 ° C. for 5 hours, and the weight (n) was measured. The graft ratio was calculated from the following equation. Here, L is the rubber content of the graft copolymer.

Graft ratio (%) = ｛[(n)-(m) ×
L] / [(m) × L]｝ × 100 (2) Reduced viscosity It was measured from a methyl ethyl ketone solution having a measuring temperature of 30 ° C. and a sample concentration of 0.4 g / dl using an Ubbelohde viscometer. (3) Glass transition temperature The glass transition temperature was measured using an automatic dynamic viscoelasticity meter (Vibron: DDV-II-EA) manufactured by Toyo Baldwin. (4) Monomer in Resin Composition Each monomer was quantitatively measured by gas chromatography of Hitachi Model 165-5052. (5) Laser marking property The measurement sample was measured at a wavelength of 10 using an Nd: YAG laser.
Marking was performed at 64 nm and measurement was performed.

Whiteness: The whiteness index of the laser mark portion was measured using a color computer (Caracom System) manufactured by Dainichi Seika Kogyo Co., Ltd. Sharpness: The part marked with a laser is visually judged, and a thin line is clearly marked, and the contrast between the base color and the marking character color is good (○); Things (×)
And

(6) Impact resistance (Izod impact) ASTM D256 (12.7 mm notch, 23
° C). (7) Heat resistance (6.4 mm DTL) The 6.4 mm load deflection temperature (DTL) of ASTM D for an injection molded product of a thermoplastic resin composition for sheet molding.
648 (1.82 MPa / cm ² ). However, only Examples 5 and 6, and Comparative Examples 14 and 15, in which a maleimide-based copolymer was blended to improve heat resistance, were measured. (8) Flame retardancy A UL test sample was prepared by injection molding and measured by a combustion test according to UL94. However, Examples 7 to 10 and Comparative Example 1 were provided with flame retardancy by adding a flame retardant and a flame retardant auxiliary.
Only 6 to 19 were measured. (9) Average Particle Diameter of Carbon Black Individual primary particle diameters (major diameters) were measured directly from a photograph of carbon black by a transmission electron microscope (TEM). The photographic magnification was 100,000 times, and the diameter of 1,000 or more primary particles was measured and calculated by arithmetic mean.

[0037]

EXAMPLES Examples and comparative examples will be described below. In the following description, "parts" indicates parts by weight.

Reference Example 1 Production of Rubber-Containing Graft Copolymer (I) A reactor purged with nitrogen was charged with 120 parts of pure water and 0.5 part of glucose.
Part, sodium pyrophosphate 0.5 part, ferrous sulfate 0.0
05 parts and polybutadiene latex (rubber particle diameter 0.3 μm, gel content 85%) 50 parts (solid content conversion)
And the temperature inside the reactor was raised to 65 ° C. while stirring. When the internal temperature reached 65 ° C., the polymerization was started, and a mixture consisting of a monomer (35 parts of styrene and 15 parts of acrylonitrile) and 0.3 part of t-dodecylmercaptan was added.
It was dripped continuously over time. At the same time, 0.25 parts of cumene hydroperoxide and potassium oleate.
An aqueous solution consisting of 5 parts and 25 parts of pure water was continuously dropped over 7 hours to complete the reaction.

The obtained graft copolymer latex was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered and dried to obtain a rubber-containing graft copolymer (I). The graft ratio of this graft copolymer (I) is 45%, and the resin component η
sp / c was 0.68 dl / g.

Reference Example 2 Maleimide copolymer (I
Production of I) In a stainless steel autoclave having a capacity of 20 L and equipped with a baffle and a Faudra type stirring blade, a methyl methacrylate / acrylamide copolymer (JP-B No. 45-2415)
A solution of 0.05 part in 165 parts of ion-exchanged water was stirred at 400 rpm, and the inside of the system was replaced with nitrogen gas. Next, acrylonitrile 10 parts styrene 50
, A mixed solution of 40 parts of N-phenylmaleimide, 0.46 part of t-dodecylmercaptan, and 0.15 part of 2,2′-azobisisobutylnitrile was added while stirring the reaction system, and the temperature was raised to 60 ° C. Then, polymerization was performed for 110 minutes. Thereafter, the temperature was raised to 100 ° C. over 50 minutes to complete the polymerization. Thereafter, the reaction system is cooled, the polymer is separated, washed and dried, and acrylonitrile 10% by weight and styrene 5
A maleimide-based copolymer (II) of 0% by weight and 40% by weight of N-phenylmaleimide was obtained. The glass transition temperature of this maleimide-based copolymer (II) was 167 ° C., and the ratio of weight average molecular weight / number average molecular weight was 2.4.

Reference Example 3 Production of Vinyl Cyanide Copolymer (III) A methyl methacrylate / acrylamide copolymer (Japanese Patent Publication No. 45-2415
A solution of 0.05 part in 165 parts of ion-exchanged water was stirred at 400 rpm, and the inside of the system was replaced with nitrogen gas. Next, 32 parts of acrylonitrile and styrene 4.
0 parts, t-dodecyl mercaptan 0.46 parts, 2,2 '
-Azobis (2,4-dimethylvaleronitrile) 0.3
9 parts, 2,2'-azobisisobutylnitrile 0.05
A part of the mixed solution was added while stirring the reaction system, and the temperature was raised to 58 ° C. to initiate polymerization. After a lapse of 15 minutes from the start of the polymerization, 64 parts of styrene from a feed pump provided at the top of the autoclave was added over 110 minutes. During this time, the reaction temperature was raised to 65 ° C. After the addition of styrene to the reaction system was completed, the temperature was raised to 100 ° C. over 50 minutes. Later,
Cooling of the reaction system, separation of the polymer,
After washing and drying, a vinyl cyanide copolymer (II) containing 10% by weight of acrylonitrile and 50% by weight of styrene was prepared.
I) was obtained. This vinyl cyanide copolymer (III)
Ηsp / c was 0.55 dl / g.

Examples 1 to 10, Comparative Examples 1 to 19 (I) Rubber-containing styrene resin described in Reference Examples, (II)
Tables 1 and 2 show ethylene / (meth) acrylate / carbon monoxide copolymer, (III) α-substituted styrene copolymer and triiron tetroxide and / or fine carbon black as coloring agent (IV). Those having the stated amount and particle size were added, mixed uniformly with a Henschel mixer, and then pelletized using a small extruder to obtain a composition. In addition, a composition obtained by adding a flame retardant and a flame retardant auxiliary in the amounts shown in Tables 1 and 2 was similarly pelletized to obtain a composition. The evaluation results are as shown in Tables 1 and 2.

[0043]

[Table 1]

[0044]

[Table 2]

From Tables 1 and 2, it can be seen that the resin composition for laser marking of the present invention is more excellent in the balance between laser marking properties and impact resistance than the resin composition of Comparative Example.

[0046]

The resin composition or molded article for laser marking of the present invention can provide clear white marking without impairing impact resistance, and is suitable for parts displaying characters and symbols.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08K 3/22 C08K 3/22 C08L 25/00 C08L 25/00 35/00 35/00 (72) Inventor Satoshi Mitsui Chiba Prefectural Ichihara City Chikusa Kaigan 2-1 Toray Industries, Inc. Chiba Plant F-term (Reference) 4F071 AA10X AA22X AA34X AA36X AA77 AB03 AB18 AD06 AE07 AE09 BA01 BB05 BB06 4F073 AA15 BA09 BA18 BA19 BA20 BA46 BA52 CA46 4J002BNXB BN06XB CD124 CG034 DA036 DE116 DE127 ED077 EJ057 FD010 FD040 FD050 FD070 FD096 FD100 FD134 FD137 FD160 GC00 GQ00

Claims (5)

[Claims] 1. A vinyl cyanide monomer (b), an aromatic vinyl monomer (c) and another vinyl monomer copolymerizable therewith in the presence of a rubbery polymer (a). 10 to 50 parts by weight of a rubber-containing graft copolymer (I) obtained by grafting at least one or more monomers selected from the group (d);
A maleimide-based copolymer consisting of 5 to 45% by weight of a vinyl cyanide-based monomer (b), 40 to 90% by weight of an aromatic vinyl-based monomer (c), and 5 to 55% by weight of a maleimide-based monomer (e) 0 to 50 parts by weight of polymer (II), 3 to 45% by weight of vinyl cyanide monomer (b), 90 to 20% by weight of aromatic vinyl monomer (c), and copolymerizable with these Resin composition A comprising 5 to 90 parts by weight of another vinyl cyanide copolymer (III) comprising 0 to 80% by weight of another vinyl copolymer (d) (provided that (I) + (II) + (III) ) =
100 parts by weight) of the coloring agent (IV) 0.0
Of the unreacted aromatic vinyl-based monomer (c), vinyl cyanide-based monomer (b) and other monomer (d) in the resulting composition. 4000 total
A resin composition for laser marking characterized by being at most ppm. 2. The resin composition for laser marking according to claim 1, wherein the maleimide monomer (e) in the maleimide copolymer (II) is N-phenylmaleimide. 3. A colorant (IV) containing 0.1 to 2 parts by weight of triiron tetroxide and / or 0.001 to 0.1 part by weight of fine carbon black having a particle diameter of 50 nm or less. The resin composition for laser marking according to claim 1. 4. The resin composition for laser marking according to claim 1, wherein 5 to 50 parts by weight of a flame retardant / flame retardant aid (V) is added to 100 parts by weight of the resin composition A. object. 5. A molded article obtained by molding the laser marking resin composition according to claim 1.